Sharpening dental burrs



(ModeL) M, A. RICHARDSON. Sharpening Dental-Burrs.

No. 226,110 Pateh ted Mar. 30, 18 80.

Fig/z Z INV EN.T0R

ATTE ST PETERS, EHQTO-LITHDGRAPHER. WASHINGTONv D C,

UNITED STATES MILO A. RICHARDSON, OF BRIDGEPORT, CONNECTICUT.

SHARPENING DENTAL BURRS.

SPECIFICATION forming part of Letters Patent No. 226,110, dated March30, 1880.

Application filed March 3, 1880.

To all whom it may concern:

Be it known that I, MILO A. RICHARDSON, of Bridgeport, in the county ofFairfield and State of Connecticut, have invented an Improved Processand Apparatus for Sharpening Dental Burrs and similar tools andinstruments, of which the following is a specification.

The object of my invention is to provide dentists and others who useburrs and similar revolving cutting-tools having inclined teeth with ahandy and rapid means of sharpening the same.

My process consists in revolving the tool backward while it is immersedin sand, corundum, or other abrasive powder or granulated substance.

My invention also consists in certain novel features in the constructionof an apparatus for the practice of this process, as will be fullyhereinafter set forth.

The cutting action of moving particles of sand, quartz-powder, corundum,and other abrasive powders and granulates upon hard bodies is wellknown, being fitly exemplified in the sand blast.

My process depends for its success upon this action, and to render itmost efiective a very sharp and hard abrasive should be selected,granulated or powdered corundum bein g well suited to the purpose.

In practicing my process the abrasive material is placed in a suitablereceptacle, and the dental burr or other tool to be sharpened isimmersed therein, and then revolved in a backward direction, or theopposite of that which is given to it in use. The particles of abrasivematerial are thus actively agitated, and at their contact with the teethof the tool they cut or abrade it sharply, thus removing the metalfromthe back of the tooth and bringing the latter to a smooth fine edge.

The revolution of the tool in the granulate causes the particles of thelatter to move and roll across its surface, and to shift and changeamong themselves so as constantly to bring fresh sharp grains into contact with the metal, and their attrition cuts away the back of the teethuntil a new edge is formed thereon, as described.

I prefer to divide the operation into two (ModeL) steps, the first thatof grinding the tool or taking a coarse cut therefrom, and the secondthat of finely finishing and polishing the same.

To accomplish the first most rapidly and effectively the tool must berevolved in the abrasive material somewhat slowly, and the materialfirmly forced or pressed against its surface, preferably by lateralpressure.

The second step is performed by revolving the tool very rapidly ineither the same or, as I prefer, a different and finer material, withoutpressure, thus completing the process.

The tool may be revolved by the use of the ordinary dental engine, or byother means, and any convenient vessel may be used as a receptacle forthe abrasive substance 5 but I prefer for the practice of my process theapparatus shown in the accompanying drawings,

in which-- Figure 1 is a front elevation, partly in section. Fig. 2 is aside elevation. Fig. 3 is a -h0lder enlarged.

Let A represent a suitable case or frame for the necessary mechanism 3B, a clock-work as a whole; 0, the spindle which bears the tool 5 D, acrank by which to rotate the spindle, and E and F receptacles for theabrasive powder or granulate. a is the last wheel of the train formingthe clock-work proper, and it meshes with a pinion, b, on the spindle c,which bears the crank D.

The crank-spindle cmay be identical with the tool-spindle C; but, as itis desirable that the latter should rotate faster than it is convenientto turn the crank, I prefer to make them separate, and to provide theformer with a wheel, (I, gearing with a pinion, e, on the latterspindle, as shown.

G is a suitable holder for the tool to be sharp ened, and may consist ofany convenient form of clutch, chuck, or socket arranged at theextremity of the spindle G, and capable of grasping the tool withsufficient force to prevent its falling out and to effect its rotationwhen immersed in the abrasive powder.

The holder G, if fixed rigidly to the extremity of the spindle 0, mustbe accurately concentric therewith, as a very slight eccentricity on thepart of the tool which is being operated upon will cause it to grindunevenly, wearing away upon one side more than upon the other. Toobviate this difiiculty I provide a flexible connection, H, between thetool and the spindle 0, whereby the tool can be deflected from the axialline of the spindle without affecting its rotation and without causingit to wabble or rotate eccentrically. This may consist of a universaljoint, or of any known form of flexible shaft, and may be eitherseparate from the tool-holder G, or, as I prefer, made in one piece withthe same, as shown. The construction of this part is best illustrated inFig. 6, a tool being shown in its place in the elastic holder, which isformed of a simple piece of rubber tube fixed to the spindle G and projecting sufficiently below it to grasp the tool and to permit asufficient deflection of the latter from the axial line of the spindle.

To accommodate tools of different lengths, the spindle may be madehollow for a short distance, that the shank of the tool may be thrust upinto it, as shown; but the inside diameter of the spindle must somewhatexceed the outside diameter of the tool-shank, or the deflection of thetool will be prevented.

The receptacle E is made of some elastic material, that its walls may bepressed together between the thumb and finger, and I prefer that it bemade with a contracted neck or throat, that its contents may not readilyescape in use.

The receptacle F is a small cup of rigid material, and is preferablymounted upon a pivoted arm or bracket, f, so as to stand back out of theway when not needed, while it can be swung out under the tool whenrequired The bracket should be capable of some vertical play, and bekept pressed upward by a spring, g, that it 'may be depressed to bringitunder the tool, and it should be provided with a catch or stop, it,setting into a-recess, h, to keep it from swinging out of place whenoperating upon the tool.

The receptacles E and F may both be employed in the process ofsharpening, or either of them may be used alone, the other beingomitted.

To sharpen a dental burr or other tool by my machine I insert its shankin the holder G, fill the receptacle E with the abrasive substance, and,holding it in the left hand, apply to the tool, so that the latter isimmersed in its contents, and with the right hand rotate the crank D,thereby turning the tool backward in the abrasive substance, at the sametime compressing the receptacle E so as to' force the particles ofabrasive closely against the revolving tool. This is continued for ashort time until the tool has been roughly sharpened or ground down, andit is then finished by permitting the clock-work B to rotate it rapidly,the pressure upon the receptacle E being released, or, as I prefer, thisreceptacle being removed and the cup F substituted for it, the lattercontaining, by preference, an abrasive of finer grain; or, if a lateralcompression is not required for the first operation, the receptacle Emay be discarded and the cup F alone used.

If the clock-work were wound up before beginning the operation, therotation of the tool by the crank would run down the spring to aconsiderable extent; and to avoid this the means shown for disconnectingthem may be used.

The spindle c is capable of a slight vertical play controlled by aslider, it, operated by a button, 1, and its swiveled stem. By raisingthe button l the spindle c is lifted until its pinion b is clear of thewheel a, the pinion e on the spindle 0 being long enough to retain thewheel (1 in engagement therewith. The apparatus, from the crank. D tothe spindle G, is now isolated from the clock-work; but to prevent thelatter from running down when thus disconnected a stop or pawl, m, mustbe arranged to engage some part of the clock-work and be operated by orfrom the button Z. This also serves to hold the clock-work while it isbeing wound up.

The button may be held up or down by a stop or pin, a, (shown in Fig.4,) which permits the button-stem to move only when turned in onedirection, as shown.

I claim 1. The improved process of sharpening a dental burr or similartool, which consists in immersing its toothed portion in sand or otherpowdered or granulated abrasive and revolving it backward therein,substantially as set forth.

2. The improved process for sharpening dental burrs and similar tools,which consists, first, in immersing the tool in an abrasive powder orgranulate, forcing the same against the tool by lateral pressure, andrevolving the tool backward therein at a comparatively low speed; and,second, in revolving the tool in the same or a finer abrasive withoutlateral pressure and at a comparatively high speed, substantially as andfor the purposes set forth.

3. The improved machine for sharpening dental burrs and other similartools, which consists of a suitable holder for the tool borne by arevolving spindle, in combination with a receptacle for sand or otherabrasive powder or granulate, whose sides are capable of being forcedtoward each other by lateral pressure, substantially as set forth.

4. The combination, with'a suitable receptacle for the abrasivesubstance, of a spindle, 0, provided with a flexible connection, H, andtool-holder Gr, substantially as set forth.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

MILO A. RICHARDSON.

Witnesses ARTHUR G. FRASER, HENRY CONNETT.

